Both high density and lower density integrated circuits are fabricated on wafers utilizing numerous fabrication techniques, including, but not limited to photolithography, masking, diffusion, ion implantation, etc. After the wafers are fabricated, with the wafer including a plurality of integrated circuit dies, a die coat is commonly used to protect the plurality of integrated circuit dies from damage during the remainder of the manufacturing process. It is commonly known to use polyimides as the buffer or die coat when fabricating such devices or wafers.
Thermosetting resins, such as cyanate esters, have been used in various applications that span electronic, structural aerospace, and microwave transparent composites as well as encapsulants and adhesives. Cyanate esters are described in the paper Arocy.RTM. Cyanate Ester Resins Chemistry, Properties and Applications, by D. A. Shimp, J. R. Christenson, and S. J. Ising (Second Edition--January 1990). Some examples of uses of cyanate esters include spinning cyanate ester onto a wafer for the purpose of making a durable base for building electric conductive metal features and also circuit board configurations.
Polyimides utilized as a spin-on die coat are somewhat expensive. Many polyimides have a high dielectric constant and do not cure very quickly. Cyanate esters on the other hand have a lower dielectric constant than most polyimides and further cure more quickly than polyimides. In addition, polyimide buffer coats do not have extremely consistent photo-imageable characteristics. For example, when using photo-masking or photolithography techniques with polyimides, such techniques are not always highly successful or reliable. Therefore, in view of the above, there is a need for improved buffer coats for the fabrication process and improved integrated circuit devices resulting therefrom.